What are the differences between National V and National VI emission standards for sedans?

[SanKevin]

The differences between National V and National VI emission standards are as follows: Different emission standards: The National VI emission standards are more than 30% stricter than National V. Excluding the influence of operating conditions and testing, gasoline vehicles' carbon monoxide emissions are reduced by 50%, total hydrocarbons and non-methane hydrocarbons emissions are reduced by 50%, and nitrogen oxide emissions are reduced by 42%. Different implementation times: The National V standard was implemented nationwide on January 1, 2017, as the fifth phase of national motor vehicle emission standards. The National VI standard has been implemented since July 1, 2019. Different principles: During the National V phase, diesel and gasoline vehicles had different emission standards, but National VI adopts a fuel-neutral principle, meaning that regardless of the fuel type, the emission limits are the same. Different issuing departments: The National V standard was issued by the Ministry of Environmental Protection. The National VI standard was issued by the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection, and Quarantine. Different letter representations: National V is represented by 'V,' while National VI is represented by 'VI.' Different monitoring requirements for plug-in hybrid electric vehicles: Compared to National V, National VI has improved monitoring requirements for plug-in hybrid electric vehicles, including energy storage systems, thermal management systems, brake regeneration, drive motors, generators, and other regulatory aspects. National V standard limits are as follows: Gasoline vehicles must not emit more than 1,000 milligrams of carbon monoxide per kilometer driven. Gasoline vehicles must not emit more than 68 milligrams of non-methane hydrocarbons per kilometer driven. Gasoline vehicles must not emit more than 60 milligrams of nitrogen oxides per kilometer driven. Gasoline vehicles must not emit more than 4.5 milligrams of PM (particulate matter) per kilometer driven. National VI has two standards: National VIa and National VIb, as follows: National VIa standard limits: Gasoline vehicles must not emit more than 700 milligrams of carbon monoxide per kilometer driven. Gasoline vehicles must not emit more than 68 milligrams of non-methane hydrocarbons per kilometer driven. Gasoline vehicles must not emit more than 60 milligrams of nitrogen oxides per kilometer driven. Gasoline vehicles must not emit more than 4.5 milligrams of PM (particulate matter) per kilometer driven. National VIb standard limits: Gasoline vehicles must not emit more than 500 milligrams of carbon monoxide per kilometer driven. Gasoline vehicles must not emit more than 35 milligrams of non-methane hydrocarbons per kilometer driven. Gasoline vehicles must not emit more than 35 milligrams of nitrogen oxides per kilometer driven. Gasoline vehicles must not emit more than 3 milligrams of PM (particulate matter) per kilometer driven. Affected by the National VI emission policy, although National V vehicles are not currently restricted in normal use (no driving bans or license plate restrictions), their resale value will be significantly impacted. For car owners, if they purchase a truck for hauling goods with a loan, the vehicle's depreciation after repaying the loan is equivalent to the net profit earned during that period. A higher residual value means more profit for the owner. Therefore, from this perspective, National VI vehicles, with longer service life and more road rights, have greater advantages.

[DelKing]

As an auto repair shop owner who frequently interacts with car owners, I’ve encountered many customers struggling with the differences between China 5 and China 6 emission standards. The fundamental distinction lies in the upgraded exhaust treatment technology. China 6 vehicles feature a three-layer defense system: optimized engine combustion to reduce raw pollutants, followed by a three-way catalytic converter to break down harmful gases, and finally a particulate filter to trap soot particles. This means China 6 vehicles must use high-quality gasoline; otherwise, sensors will immediately trigger fault codes. Emission testing has also become significantly stricter—China 6 vehicles we service typically emit only about one-third of the pollutants compared to China 5 vehicles. However, it’s important to note that China 6 is divided into two phases (a and b), and some early China 6 models merely added an OBD monitoring system, resulting in a gap in actual purification capability compared to later models.

[EvanFitz]

Last year when I changed cars, I specifically researched this. The most visible difference between China 5 and China 6 standards is on the fuel cap: China 6 vehicles must be labeled 'Please use gasoline compliant with Phase VI standards'. In terms of performance, the same engine model in China 6 version is about 5% weaker due to emission control measures that reduce power output. The used car market shows even greater disparity – major cities now prohibit transfer registration of China 5 vehicles. My old China 5 car was rejected by three cities during inter-provincial relocation. Driving a China 6 car has an unexpected benefit: you barely smell exhaust during stop-start traffic jams, a sensation that becomes particularly noticeable when seeing buses emit black smoke at red lights.

[VonAlyssa]

In simple terms, it's a comprehensive upgrade in purification technology. The China VI standard has nearly halved the pollutant limits, for example, reducing nitrogen oxide limits from 60mg/km under China V to 35mg/km. To achieve this, vehicles are now equipped with real-time monitoring OBD systems, honeycomb-shaped particulate filters (DPF) installed in the exhaust pipes, and redesigned catalytic converter coatings. Observing the exhaust pipe outlets on the road, China VI vehicles hardly accumulate carbon soot. The latest report from the Environmental Protection Agency shows that after the nationwide switch to China VI, the contribution rate of vehicle exhaust to PM2.5 dropped by 18%.

[CeciliaLee]

Don't be fooled by emission standard letters - China 6 actually has 'real 6' and 'fake 6'. The 6a standard is transitional, with some automakers achieving compliance simply by reprogramming ECUs. The truly rigorous 6b phase mandates urea injection systems (for diesel vehicles) or GPF particulate filters (for gasoline models). Here's a lesser-known fact: China 6-compliant versions of the same car model have 8% larger fuel tanks than their China 5 counterparts - designed to offset the weight added by new emission control devices. My neighbor bought a cheaper China 5 vehicle, and now constantly worries about urban driving restrictions during holidays, as 87 major cities have already implemented China 6 access policies.

[DianaFitz]

For those who frequently check the used car market, here's how to distinguish: China 6 vehicles are like furnished apartments, while China 5 are the basic versions. Buying a new China 6 car might cost a few thousand more, but it holds higher residual value when reselling. Technically, the higher cost mainly comes from sensors – a China 6 car uses four oxygen sensors alone. Maintenance is more complex for China 6 vehicles, such as requiring professional regeneration of the particulate filter every 80,000 km. An interesting finding: China 6 models average 0.3L/100km lower fuel consumption than China 5 due to optimized combustion efficiency. Be wary of deceptive dealers – always verify the environmental compliance list: authentic China 6 vehicles must have the 'CN6b' mark in their official announcements.